Wednesday, November 30, 2005

solar power

nov 30

one of the objections to solar power (by which i mean photovoltaics converting sunlight into electricity) are that the energy density is too small to replace conventional power plants. that may well be true, but nobody is talking about replacing conventional power plants overnight. it is a matter of coexistence between today's generating plants and the new technology.

an excellent example in real life is the emergence of the hybrid automobile. it is not displacing conventional cars but will slowly increase its market share as oil prices remain at historic highs. the same will happen to solar power devices as well: they will emerge where they make sense, in smaller applications. they probably will never completely displace coal-fired or oil-fired or nuclear-powered electricity plants.

but there is another observation that needs to be taken into account: that of low-end technologies that rapidy become substitutes for high-end technologies, if the innovation curve is steep enough. the low-end stuff that appears almost toy-like, completely unable to solve the problems high-end products are able to tackle: that is quintessentially what a new innovation typically looks like.

however, in some instances, the low-end product can become more and more powerful quickly so that it soon starts becoming an adequate replacement for the high-end products, which are not evolving quite as rapidly, partly because they are the incumbent. this has happened in the computer industry where the mini-computer and then engineering workstations and finally the PC have all marched rapidly up the value curve and shoved the incumbent products aside.

at the moment, it is not clear that solar power falls into this category where innovation drives a rapid rise up the curve. it probably does not, and that might be a result of the fact that most western countries, not being rich in solar power, are not putting much effort into developing photovoltaics, as that is not going to lead to much demand in their (rich) nations. this is analogous to pharmaceutical companies not spending research money on tropical diseases, instead concentrating on drugs for more lucrative diseases such as cancer, diabetes, high cholesterol, etc which have readier in their home countries.

but if developing countries such as india take more interest and actually invest money, it is likely that solar energy will become a big factor. this would have a lot of benefits for india: getting off the crack-like addiction that the west has for oil; perhaps increased investment into public transport rather than cars; the reduction in the import bill for oil; and indirectly the reduction in the funds that flow to pakistan from the arab world for terrorism against india.

here's some information from wired magazine about solar energy:,1367,68840,00.html?tw=wn_story_related


Kalyani said...

"Sun God creates a culinary miracle at Shirdi Dharamshala"

"The idea of using the sun to cook for his devotees would surely have appealed to the mystic of Shirdi, who ,once lit his wicklamps with water instead of oil"

"An array of parabolic mirrors create temperatures of 550-650 degrees celsius by focussing sun's rays.The intense heat generated at the focal point of each mirror is used to convert water into steam..piped to feed the steam cooking vessels in the kitchen.

Deepak Gadhia's Valsad based firm installed the system for Brahmakumaris at Mt.Abu and Shirdi"

That is a fairly old writeup, I have posted.

Thiruvannamalai Ashramam has solar water heaters, I have seen.I have also
been to Vallimalai Ashramam atop a hill, which uses biogas for cooking.They have a few cows and the dung is effectively used thus. The cows' fodder is purely organic.

san said...

To me, the most value-added use of solar power and wind power are in distributed power generation. Meaning deploying it places which are hard to wire up to the conventional electricity grid. This opens up better possibilities for rural development, with solar- and wind-powered allowing rural dwellers to meet their power needs without waiting for the slow pace of electric grid expansion to make it out to them. Also consider that you avoid the power losses associated with transmitting electricity across power transmission lines. Solar and Wind power installations are expensive right now, but mass production could help make the cost come down, and in the process India could also sell such installations to the export market.

Solar street lamps are already being trialed in Coimbatore, which is also already India's windpower capital too. One company is even rolling out a solar street lamp with Wi-Fi antenna relay built in, so that people nearby can even use it to surf the net. It's debuting in Kenya, with plans to roll it out in India, China, etc too.

san said...

Wave power has been combined with desalination for a more efficient overall process:

Perhaps it could help coastal states like Tamil Nadu and Karnataka get more fresh water for drinking and irrigation, so that they won't fight over water rights so much.

san said...

Deccan Chronicle , 8 July 2005

More water? Lower rice yields

By L.C. Jain

Mexico gave us the magic wand for wheat revolution some decades ago. Now the small island of Madagascar, off the Mozambique coast, has sent India a heavenly gift: System of Rice Intensification (SRI), a new method of rice cultivation. Count your blessings. Under SRI, paddy needs only half the volume of water consumed by the conventional method of rice cultivation. First, this means doubling the irrigation coverage for paddy with no extra rupee to be spent on augmenting irrigation supply. Second, it raises paddy yields by 50 per cent at the same time. Hard to believe, isn’t it?

But my disbelief vanished in thin air listening to hundreds of farmers from the southern states of Tamil Nadu, Andhra Pradesh, Karnataka and Kerala at a convention organised by Jala Spandana on May 26 at Bangalore. The clinching evidence came from a woman farmer, S. Poongodi of Erode: She has adapted SRI over her entire two acres of land since 1999. This year she tried new experiments in the SRI, depending upon her soil features.

She cultivated the traditional variety, called “Ponni”, a fine rice variety. In one portion of her land she followed the regular SRI method of planting younger seedlings, wide spacing, shallow planting, intermittent watering. In another portion, which is seepage-affected area, she raised nursery beds after dry ploughing and transplanted the seedlings in the raised beds after irrigation. In another small patch of land she tried just throwing the seedlings instead of planting.

In all the fields she applied one tonne of Vermi compost as the fertiliser. A herbal decoction to repel leaf rollers, and other insects that cause damage, was sprayed twice in this crop season. In addition, she sprayed a special brew called “Panchakavya”, a brew made out of cow dung, cow’s urine, milk, curd and ghee. This brew is widely used by organic farmers to promote disease resistance, drought resistance, and for increasing the yield. The coconut milk and buttermilk combination is used as a growth promoter.

The average yield per acre obtained by Poongodi under SRI is 2161.57 kg, about 50 per cent higher than the 1,560 kg per acre obtained by non-SRI farmers. Poongodi, of course, got an added bonus for her adventurous spirit. The entire produce was purchased by an admiring consumer at Rs 3,450 per pothi (260 kg). During this time the same variety of rice with non-SRI fetched Rs 1,600 per pothi.

At the end she delivered a startling message of great impact to the country. Poongodi says happily, “When fellow farmers were fighting for water in the command area, I was watchfully avoiding more water into my field as it proved that more water means less yield.” What a magical solution to the core problem of the farming community. Farmers from Karnataka and Tamil Nadu said this means that they don’t have to break each other’s heads for sharing scarce water.

The SRI method has doubled the availability. They cited this as an example of finding solutions by the community itself, and not waiting for the endless inter-state water disputes to be resolved. How one wishes the Prime Minister and chief ministers were listening.

They beamed this message to Karnataka’s law and parliamentary affairs minister, H.K. Patil, who chaired the farmers’ convention. They reiterated, “Please promote the SRI method of paddy cultivation, which requires less water, to save water and prevent inter-state disputes.” Patil was not only one with them, but was one up. He said in his water scarce district Gadag, several farmers were already trying the SRI method — and with equally encouraging results — maximising yields, minimising water use. He was busy advocating its spread.

“Such methods should be popularised as their use will help in ending water disputes between states,” he said. Patil added: “Because the state borrows from external agencies, such as the Asian Development Bank and the World Bank, these agencies tell us what we should do. But this does not mean we do not know anything. We should think of ways of resolving inter-state water disputes, and it can happen through the use of advanced technology in cultivation.”

The good news is that our agricultural scientists and universities have responded to Madagascar SRI technology very seriously. In Tamil Nadu, during experiments in 2003-04 at Agricultural College and Research Institute, Tamil Nadu Agricultural University, Killkulam, found that on average 53 per cent less irrigation water was used on SRI farms. The experiments showed that SRI recorded higher water productivity of 0.699 kg/m3 compared to conventional farm productivity.

The partial factor productivity of nitrogen was 28.3 per cent more under SRI. SRI farms recorded a grain yield of 3892.7 kg/ha, 28 per cent higher than that from conventional farms. The Tamil Nadu Agricultural University has recommended SRI as a technology to increase rice productivity and save irrigation water.

In Andhra, on-farm demonstrations were organised in all 22 rural districts for SRI in Kharif 2003 by Acharya N.G. Ranga Agricultural University, Hyderabad. A study done after contacting 291 respondents, including 67 SRI farmers, 71 neighbouring farmers, 77 researchers and 76 extension workers, found that in SRI farms, 95 per cent of seeds were saved as a seed rate of 5 kg/ha was sufficient, about 50 per cent of water was saved and an average yield advantage of 2 tonnes per ha was reported. Some of the difficulties faced by SRI farmers were in use of rotary weeders, transplantation of young seeds and water management. They all reported that the plants looked much healthier on SRI farms.

AB said...

I think exploring alternative energy is an excellent idea. I also think that India should pursue a multipronged approach, i.e., not stick to just one technology, but try and complement solar with other alternative sources. In a lot of rural areas gobar gas is an excellent form of alternative energy, when built right. Anaerobic digestion will also work wonders in most of India because of the relatively high temperatures that are needed for bacterial action. I speak about anaerobic digestion from experience. My grandmother's house in Dakshina Kannada has not bought an LPG cylinder in years just because she has gobar gas now. I am sure that if they invested in some wind and solar, their house could get almost uninterrupted power for most of the year. The electricity provided by the gov't is so bad that almost anything else will be much better in comparison!

DarkStorm said...

Well yes rajeev, you are right. The energy density is less for solar power(using photo voltaic cells).

But it can be used to supplement the current energy sources. But it can be fine enough to light up stuff. We already have 20 watt coiled flourescent lamps, 2 of which can give more light than a tubelight. More power efficient!. Solar power is most abundant in India, not wind power.

Solar power needs to be researched. Better photovoltaic cells needed. Even wind power cannot replace conventional power plants. Cant we have simple photovoltaic chargers to recharge batteries, invertors, etc. Also solar power, combined with fuel cells is one very effective combination. A good way to generate electric power.

I have seen good photovoltaic implementations, good enough to generate quite some power. There have been successful experiments to superheat pressurized steam, using concentrating mirrors. That can be a steam power plant covering some big area, backed up by a coal boiler.

Why cant we have solar heaters to preheat the water that is heated to steam in steam turbine power plants, which use superheated steam.

Preheating and economizing (kind of turbocharging and supercharging done with IC engines) in power plants increases efficiency quite a lot. Basically it is like, the exhaust gases of diesel engines is used to drive a small low capacity turbine before final exhaust, which compresses the intake air to some extent. Diesel engines work on higher compression. This is the mechanism that many auto makers advertize as TurboDiesel, or Turbo or whatever.

DarkStorm said...

Given the concern for the environment, even tidal and hydel power plants are unpreferable. They dont cause air pollution, but mess up the river and delta ecosystems, in the long run.

It is either wind, sun or ocean power plants for us. Ocean power plants... Well this is a complex system which uses the temperature difference between the deep waters and surface waters to generate electricity, mostly at experimental stages. ..

Guess, wind turbines that operate at low / very low wind speeds is what is needed in India. San posted a link on that. But, most of India has much less winds, to even make use of those turbines. Wind turbines are most effective in coastal areas, not the inlands. Come what may, we have to invest in all sources of power, including thorium power plants.

I dont know what happened to those gas finds in Rajasthan and Krishna Godavari basins. If anyone has any knowledge bout that, please post. All i can find in google is the news reports.

Kalyani said...

"Given the concern for the environment, even tidal and hydel power plants are unpreferable. They dont cause air pollution, but mess up the river and delta ecosystems, in the long run".


Also , slaughter of animals,need to be stopped;Maneka Gandhi has written extensively on it.We are paying huge amounts to import cow dung from European countries.